AN ELEMENTARY STUDY OF CHEMISTRY pot

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AN ELEMENTARY STUDY OF CHEMISTRY pot

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AN ELEMENTARY STUDY OF CHEMISTRY BY WILLIAM McPHERSON, PH.D PROFESSOR OF CHEMISTRY, OHIO STATE UNIVERSITY AND WILLIAM EDWARDS HENDERSON, PH.D ASSOCIATE PROFESSOR OF CHEMISTRY, OHIO STATE UNIVERSITY REVISED EDITION GINN & COMPANY BOSTON * NEW YORK * CHICAGO * LONDON COPYRIGHT, 1905, 1906, BY WILLIAM MCPHERSON AND WILLIAM E HENDERSON ALL RIGHTS RESERVED The Athenæum Press GINN & COMPANY * PROPRIETORS * BOSTON * U.S.A Transcriber's note: Minor typos have been corrected PREFACE In offering this book to teachers of elementary chemistry the authors lay no claim to any great originality It has been their aim to prepare a text-book constructed along lines which have become recognized as best suited to an elementary treatment of the subject At the same time they have made a consistent effort to make the text clear in outline, simple in style and language, conservatively modern in point of view, and thoroughly teachable The question as to what shall be included in an elementary text on chemistry is perhaps the most perplexing one which an author must answer While an enthusiastic chemist with a broad understanding of the science is very apt to go beyond the capacity of the elementary student, the authors of this text, after an experience of many years, cannot help believing that the tendency has been rather in the other direction In many texts no mention at all is made of fundamental laws of chemical action because their complete presentation is quite beyond the comprehension of the student, whereas in many cases it is possible to present the essential features of these laws in a way that will be of real assistance in the understanding of the science For example, it is a difficult matter to deduce the law of mass action in any very simple way; yet the elementary student can readily comprehend that reactions are reversible, and that the point of equilibrium depends upon, rather simple conditions The authors believe that it is worth while to[Pg iv] present such principles in even an elementary and partial manner because they are of great assistance to the general student, and because they make a foundation upon which the student who continues his studies to more advanced courses can securely build The authors have no apologies to make for the extent to which they have made use of the theory of electrolytic dissociation It is inevitable that in any rapidly developing science there will be differences of opinion in regard to the value of certain theories There can be no question, however, that the outline of the theory of dissociation here presented is in accord with the views of the very great majority of the chemists of the present time Moreover, its introduction to the extent to which the authors have presented it simplifies rather than increases the difficulties with which the development of the principles of the science is attended The oxygen standard for atomic weights has been adopted throughout the text The International Committee, to which is assigned the duty of yearly reporting a revised list of the atomic weights of the elements, has adopted this standard for their report, and there is no longer any authority for the older hydrogen standard The authors not believe that the adoption of the oxygen standard introduces any real difficulties in making perfectly clear the methods by which atomic weights are calculated The problems appended to the various chapters have been chosen with a view not only of fixing the principles developed in the text in the mind of the student, but also of enabling him to answer such questions as arise in his laboratory work They are, therefore, more or less practical in character It is not necessary that all of them should[Pg v] be solved, though with few exceptions the lists are not long The answers to the questions are not directly given in the text as a rule, but can be inferred from the statements made They therefore require independent thought on the part of the student With very few exceptions only such experiments are included in the text as cannot be easily carried out by the student It is expected that these will be performed by the teacher at the lecture table Directions for laboratory work by the student are published in a separate volume While the authors believe that the most important function of the elementary text is to develop the principles of the science, they recognize the importance of some discussion of the practical application of these principles to our everyday life Considerable space is therefore devoted to this phase of chemistry The teacher should supplement this discussion whenever possible by having the class visit different factories where chemical processes are employed Although this text is now for the first time offered to teachers of elementary chemistry, it has nevertheless been used by a number of teachers during the past three years The present edition has been largely rewritten in the light of the criticisms offered, and we desire to express our thanks to the many teachers who have helped us in this respect, especially to Dr William Lloyd Evans of this laboratory, a teacher of wide experience, for his continued interest and helpfulness We also very cordially solicit correspondence with teachers who may find difficulties or inaccuracies in the text The authors wish to make acknowledgments for the photographs and engravings of eminent chemists from which[Pg vi] the cuts included in the text were taken; to Messrs Elliott and Fry, London, England, for that of Ramsay; to The Macmillan Company for those of Davy and Dalton, taken from the Century Science Series; to the L E Knott Apparatus Company, Boston, for that of Bunsen THE AUTHORS OHIO STATE UNIVERSITY COLUMBUS, OHIO [Pg vii] CONTENTS CHAPTER PAGE I INTRODUCTION II OXYGEN 13 III HYDROGEN 28 IV WATER AND HYDROGEN DIOXIDE 40 V THE ATOMIC THEORY 59 VI CHEMICAL EQUATIONS AND CALCULATIONS 68 VII NITROGEN AND THE RARE ELEMENTS IN THE ATMOSPHERE 78 VIII THE ATMOSPHERE 83 IX SOLUTIONS 94 X ACIDS, BASES, AND SALTS; NEUTRALIZATION 106 XI VALENCE 116 XII COMPOUNDS OF NITROGEN 122 XIII REVERSIBLE REACTIONS AND CHEMICAL EQUILIBRIUM 137 XIV SULPHUR AND ITS COMPOUNDS 143 XV PERIODIC LAW 165 XVI THE CHLORINE FAMILY 174 XVII CARBON AND SOME OF ITS SIMPLER COMPOUNDS 196 XVIII FLAMES,—ILLUMINANTS 213 XIX MOLECULAR WEIGHTS, ATOMIC FORMULAS WEIGHTS, 223 XX THE PHOSPHORUS FAMILY 238 XXI SILICON, TITANIUM, BORON 257 XXII THE METALS 267 XXIII THE ALKALI METALS 274 XXIV THE ALKALINE-EARTH FAMILY 300 XXV THE MAGNESIUM FAMILY 316 XXVI THE ALUMINIUM FAMILY 327 XXVII THE IRON FAMILY 338 XXVIII COPPER, MERCURY, AND SILVER 356 XXIX TIN AND LEAD 370 XXX MANGANESE AND CHROMIUM 379 XXXI GOLD AND THE PLATINUM FAMILY 390 XXXII SOME SIMPLE ORGANIC COMPOUNDS 397 INDEX 421 Facing APPENDIX A cover Inside APPENDIX B cover [Pg ix] LIST OF FULL-PAGE ILLUSTRATIONS PAGE ANTOINE LAURENT LAVOISIER Frontispiece JOSEPH PRIESTLEY 14 JOHN DALTON 60 WILLIAM RAMSAY 82 DMITRI IVANOVITCH MENDELÉEFF 166 HENRI MOISSAN 176 SIR HUMPHRY DAVY 276 ROBERT WILHELM BUNSEN 298 [Pg 1] AN ELEMENTARY STUDY OF CHEMISTRY CHAPTER I INTRODUCTION back back The natural sciences Before we advance very far in the study of nature, it becomes evident that the one large study must be divided into a number of more limited ones for the convenience of the investigator as well as of the student These more limited studies are called the natural sciences Since the study of nature is divided in this way for mere convenience, and not because there is any division in nature itself, it often happens that the different sciences are very intimately related, and a thorough knowledge of any one of them involves a considerable acquaintance with several others Thus the botanist must know something about animals as well as about plants; the student of human physiology must know something about physics as well as about the parts of the body Intimate relation of chemistry and physics Physics and chemistry are two sciences related in this close way, and it is not easy to make a precise distinction between them In a general way it may be said that they are both concerned with inanimate matter rather than with living, and more particularly with the changes which such matter[Pg 2] may be made to undergo These changes must be considered more closely before a definition of the two sciences can be given Physical changes One class of changes is not accompanied by an alteration in the composition of matter When a lump of coal is broken the pieces not differ from the original lump save in size A rod of iron may be broken into pieces; it may be magnetized; it may be heated until it glows; it may be melted In none of these changes has the composition of the iron been affected The pieces of iron, the magnetized iron, the glowing iron, the melted iron, are just as truly iron as was the original rod Sugar may be dissolved in water, but neither the sugar nor the water is changed in composition The resulting liquid has the sweet taste of sugar; moreover the water may be evaporated by heating and the sugar recovered unchanged Such changes are called physical changes DEFINITION: Physical changes are those which not involve a change in the composition of the matter Chemical changes Matter may undergo other changes in which its composition is altered When a lump of coal is burned ashes and invisible gases are formed which are entirely different in composition and properties from the original coal A rod of iron when exposed to moist air is gradually changed into rust, which is entirely different from the original iron When sugar is heated a black substance is formed which is neither sweet nor soluble in water Such changes are evidently quite different from the physical changes just described, for in them new substances are formed in place of the ones undergoing change Changes of this kind are called chemical changes.[Pg 3] DEFINITION: Chemical changes are those which involve a change in the composition of the matter How to distinguish between physical and chemical changes It is not always easy to tell to which class a given change belongs, and many cases will require careful thought on the part of the student The test question in all cases is, Has the composition of the substance been changed? Usually this can be answered by a study of the properties of the substance before and after the change, since a change in composition is attended by a change in properties In some cases, however, only a trained observer can decide the question Changes in physical state One class of physical changes should be noted with especial care, since it is likely to prove misleading It is a familiar fact that ice is changed into water, and water into steam, by heating Here we have three different substances,—the solid ice, the liquid water, and the gaseous steam,—the properties of which differ widely The chemist can readily show, however, that these three bodies have exactly the same composition, being composed of the same substances in the same proportion Hence the change from one of these substances into another is a physical change Many other substances may, under suitable conditions, be changed from solids into liquids, or from liquids into gases, without change in composition Thus butter and wax will melt when heated; alcohol and gasoline will evaporate when exposed to the air The three states—solid, liquid, and gas—are called the three physical states of matter Physical and chemical properties Many properties of a substance can be noted without causing the substance to undergo chemical change, and are therefore called its physical properties Among these are its physical state, color, odor, taste, size, shape, weight Other properties are only[Pg 4] discovered when the substance undergoes chemical change These are called its chemical properties Thus we find that coal burns in air, gunpowder explodes when ignited, milk sours when exposed to air Definition of physics and chemistry It is now possible to make a general distinction between physics and chemistry DEFINITION: Physics is the science which deals with those changes in matter which not involve a change in composition DEFINITION: Chemistry is the science which deals with those changes in matter which involve a change in composition Two factors in all changes In all the changes which matter can undergo, whether physical or chemical, two factors must be taken into account, namely, energy and matter Energy It is a familiar fact that certain bodies have the power to work Thus water falling from a height upon a water wheel turns the wheel and in this way does the work of the mills Magnetized iron attracts iron to itself and the motion of the iron as it moves towards the magnet can be made to work When coal is burned it causes the engine to move and transports the loaded cars from place to place When a body has this power to work it is said to possess energy Law of conservation of energy Careful experiments have shown that when one body parts with its energy the energy is not destroyed but is transferred to another body or system of bodies Just as energy cannot be destroyed, neither can it be created If one body gains a certain amount of energy, some other body has lost an equivalent amount.[Pg 5] These facts are summed up in the law of conservation of energy which may be stated thus: While energy can be changed from one form into another, it cannot be created or destroyed Transformations of energy Although energy can neither be created nor destroyed, it is evident that it may assume many different forms Thus the falling water may turn the electric generator and produce a current of electricity The energy lost by the falling water is thus transformed into the energy of the electric current This in turn may be changed into the energy of motion, as when the current is used for propelling the cars, or into the energy of heat and light, as when it is used for heating and lighting the cars Again, the energy of coal may be converted into energy of heat and subsequently of motion, as when it is used as a fuel in steam engines Since the energy possessed by coal only becomes available when the coal is made to undergo a chemical change, it is sometimes called chemical energy It is this form of energy in which we are especially interested in the study of chemistry Matter Matter may be defined as that which occupies space and possesses weight Like energy, matter may be changed oftentimes from one form into another; and since in these transformations all the other physical properties of a substance save weight are likely to change, the inquiry arises, Does the weight also change? Much careful experimenting has shown that it does not The weight of the products formed in any change in matter always equals the weight of the substances undergoing change Law of conservation of matter The important truth just stated is frequently referred to as the law of conservation[Pg 6] of matter, and this law may be briefly stated thus: Matter can neither be created nor destroyed, though it can be changed from one form into another Classification of matter At first sight there appears to be no limit to the varieties of matter of which the world is made For convenience in study we may classify all these varieties under three heads, namely, mechanical mixtures, chemical compounds, and elements action as an acid 157 action on metals 157 action on organic matter 158 action on salts 158 [Pg 433]action on water 158 fuming 155 manufacture 154 oxidizing action 157 plant 156 properties 157 salts 159 Sulphuric anhydride 153 Sulphurous acid 151 Superphosphate of lime 246 Sylvine 288 Symbols 11 Synthesis 40 Table, alkali metals 274 alkaline-earth metals 300 alloys of copper 359 aqueous tension Appendix B atomic weights Appendix A chlorine family 174 composition of earth's crust 10 composition of fuel gases 220 constants of elements Appendix B copper family 356 elements Appendix A gold and platinum metals 390 hydrocarbons 399 magnesium family 316 manganese and chromium 379 periodic arrangement 168 phosphorus family 238 silicon family 257 solubility of gases in water 95 solubility of salts 96 solubility of salts at different temperatures 97 tin and lead 370 weights of gases Appendix B Talc 321, 336 Tartar emetic 408 Tartaric acid 408 Tellurium 161 Temporary hardness 309 Ternary acids 113 salts 114 Tetraboric acid 265 Thallium 327 Theory, atomic 61 definition 64 value of 64 Thermite 331 Thio compounds 282 Thiosulphates 159 Thiosulphuric acid 159 Thorium 377 Tin 370 block 371 compounds 372 crystals 372 family 370 foil 371 metallurgy 370 plate 371 properties 371 uses 371 Titanium 257, 264 Topaz 331 Triad families 166 Tungsten 388 Type metal 253, 375 Uranium 388 Valence 116 a numerical property 116 and combining ratios 118 and equations 120 and formulas 120 and periodic groups 162 and structure 118 definition 116 indirectly determined 117 measure of 117 variable 117 Vaseline 400 Venetian red 349 Verdigris 407 Vermilion 363 Vinegar 406 Vitriol, blue 361 green 350 oil of 154 white 324 Volume and aqueous tension 25 and pressure 24 and temperature 23 of combining gases 194 Water 40 a compound 40 [Pg 434]and disease 49 catalytic action of 154 chalybeate 351 chemical properties 53 composition 47 composition by volume 44 composition by weight 47 dissociation of 210 distillation of 50 electrolysis of 41, 103 filtration of 51 gas 219 hard 309 historical 40 impurities in 48 in air 87 mineral 49 occurrence 48 of crystallization 54, 75 physical properties 53 purification of 50 qualitative analysis 41 quantitative analysis 42 river 49 sanitary analysis 50 self-purification 53 softening of 310 standard substance 55 synthesis 43 uses of 55 Weights, atomic 65 Welsbach mantles 219, 377 Whisky 404 Wine 404 Witherite 312 Wood alcohol 402 distillation 402 Wood's metal 254 Xenon 80 Yeast 403 Zinc 321 alloys of 323 blende 321 chloride 325 flowers of 322 metallurgy 321 occurrence 321 oxide 324 sulphate 324 sulphide 325 white 324 Zymase, 403 ANNOUNCEMENTS AN ELEMENTARY STUDY OF CHEMISTRY By WILLIAM McPHERSON, Professor of Chemistry in Ohio State University, and WILLIAM E HENDERSON, Associate Professor of Chemistry in Ohio State University 12mo Cloth 434 pages Illustrated List price, $1.25; mailing price, $1.40 This book is the outgrowth of many years of experience in the teaching of elementary chemistry In its preparation the authors have steadfastly kept in mind the limitations of the student to whom chemistry is a new science They have endeavored to present the subject in a clear, well-graded way, passing in a natural and logical manner from principles which are readily understood to those which are more difficult to grasp The language is simple and as free as possible from unusual and technical phrases Those which are unavoidable are carefully defined The outline is made very plain, and the paragraphing is designed to be of real assistance to the student in his reading The book is in no way radical, either in the subject-matter selected or in the method of treatment At the same time it is in thorough harmony with the most recent developments in chemistry, both in respect to theory and discovery Great care has been taken in the theoretical portions to make the treatment simple and well within the reach of the ability of an elementary student The most recent discoveries have been touched upon where they come within the scope of an elementary text Especial attention has been given to the practical applications of chemistry, and to the description of the manufacturing processes in use at the present time EXERCISES IN CHEMISTRY By WILLIAM McPHERSON and WILLIAM E HENDERSON (In press.) GINN & COMPANY PUBLISHERS A FIRST COURSE IN PHYSICS By ROBERT A MILLIKAN, Associate Professor of Physics, and HENRY G GALE, Assistant Professor of Physics in The University of Chicago 12mo, cloth, 488 pages, illustrated, $1.25 A LABORATORY COURSE IN PHYSICS FOR SECONDARY SCHOOLS By ROBERT A MILLIKAN and HENRY G GALE 12mo, flexible cloth, 134 pages, illustrated, 40 cents This one-year course in physics has grown out of the experience of the authors in developing the work in physics at the School of Education of The University of Chicago, and in dealing with the physics instruction in affiliated high schools and academies The book is a simple, objective presentation of the subject as opposed to a formal and mathematical one It is intended for the third-year high-school pupils and is therefore adapted in style and method of treatment to the needs of students between the ages of fifteen and eighteen It especially emphasizes the historical and practical aspects of the subject and connects the study very intimately with facts of daily observation and experience The authors have made a careful distinction between the class of experiments which are essentially laboratory problems and those which belong more properly to the classroom and the lecture table The former are grouped into a Laboratory Manual which is designed for use in connection with the text The two books are not, however, organically connected, each being complete in itself All the experiments included in the work have been carefully chosen with reference to their usefulness as effective classroom demonstrations GINN AND COMPANY PUBLISHERS APPENDIX A LIST OF THE ELEMENTS, THEIR SYMBOLS, AND ATOMIC WEIGHTS The more important elements are marked with an asterisk O = 16 *Antimony Sb 120.2 *Argon A *Arsenic As 75.0 *Barium Ba 137.4 Beryllium Be 9.1 *Bismuth Bi 208.5 *Boron B *Bromine Br 79.96 *Cadmium Cd 112.4 Cæsium Cs 132.9 *Calcium Ca 40.1 *Carbon C Cerium Ce 140.25 *Chlorine Cl 35.45 39.9 11.0 12.00 *Chromium Cr 52.1 *Cobalt Co 59.0 Columbium Cb 94.0 *Copper Cu 63.6 Erbium Er 166.0 *Fluorine F Gadolinium Gd 156.0 Gallium Ga 70.0 Germanium Ge 72.5 *Gold Au 197.2 Helium He 4.0 *Hydrogen H 1.008 Indium In 115.0 *Iodine I 126.97 Iridium Ir 193.0 *Iron Fe 55.9 Krypton Kr 81.8 Lanthanum La 138.9 *Lead Pb 206.9 Lithium Li 7.03 *Magnesium Mg 24.36 *Manganese Mn 55.0 *Mercury Hg 200.0 Molybdenum Mo 96.0 19.0 Neodymium Nd 143.6 Neon Ne 20.0 *Nickel Ni 58.7 *Nitrogen N Osmium Os 191.0 *Oxygen O Palladium Pd 106.5 *Phosphorus P 31.0 *Platinum Pt 194.8 *Potassium K 39.15 14.04 16.00 Praseodymium Pr 140.5 Radium Ra 225.0 Rhodium Rh 103.0 Rubidium Rb 85.5 Ruthenium Ru 101.7 Samarium Sm 150.3 Scandium Sc 44.1 Selenium Se 79.2 *Silicon Si *Silver Ag 107.93 *Sodium Na 23.05 *Strontium Sr 87.6 *Sulphur S Tantalum Ta 183.0 28.4 32.06 Tellurium Te 127.6 Terbium Tb 160.0 Thallium Tl 204.1 Thorium Th 232.5 Thulium Tm 171.0 *Tin Sn 119.0 Titanium Ti 48.1 Tungsten W 184.0 Uranium U 238.5 Vanadium V 51.2 Xenon Xe 128.0 Ytterbium Yb 173.0 Yttrium Yt 89.0 *Zinc Zn 65.4 Zirconium Zr 90.6 APPENDIX B Tension of Aqueous Vapor expressed in Millimeters of Mercury TEMPERATURE PRESSURE 16 13.5 17 14.4 18 15.3 19 16.3 20 17.4 21 18.5 22 19.6 23 20.9 24 22.2 25 23.5 Weight of Liter of Various Gases measured under Standard Conditions Acetylene 1.1614 Air 1.2923 Ammonia 0.7617 Carbon dioxide 1.9641 Carbon monoxide 1.2499 Chlorine 3.1650 Hydrocyanic acid 1.2036 Hydrochloric acid 1.6275 Hydrogen 0.08984 Hydrosulphuric acid 1.5211 Methane 0.7157 Nitric oxide 1.3410 Nitrogen 1.2501 Nitrous oxide 1.9677 Oxygen 1.4285 Sulphur dioxide 2.8596 Densities and Melting Points of Some Common Elements DENSITY MELTING POINT Aluminium 2.68 640 Antimony 6.70 432 Arsenic 5.73 — Barium 3.75 — Bismuth 9.80 270 Boron 2.45 — Cadmium 8.67 320 Cæsium 1.88 26.5 Calcium 1.54 — Carbon, Diamond 3.50 — " Graphite 2.15 — " Charcoal 1.80 — Chromium 7.30 3000 Cobalt 8.55 1800 Copper 8.89 1084 Gold 19.30 1064 Iridium 22.42 1950 Iron 7.93 1800 Lead 11.38 327 Lithium 0.59 186 Magnesium 1.75 750 Manganese 8.01 1900 Mercury 13.596 -39.5 Nickel 8.9 1600 Osmium 22.47 — Palladium 11.80 1500 Phosphorus 1.80 45 Platinum 21.50 1779 Potassium 0.87 62.5 Rhodium 12.10 — Rubidium 1.52 38.5 Ruthenium 12.26 — Silicon 2.35 — Silver 10.5 960 Sodium 0.97 97.6 Strontium 2.50 — Sulphur 2.00 114.8 Tin 7.35 235 Titanium 3.50 — Zinc 7.00 420 ... composition of the substance been changed? Usually this can be answered by a study of the properties of the substance before and after the change, since a change in composition is attended by a change... combustion of any substance are called products of combustion of that substance Thus oxide of sulphur is the product of the combustion of sulphur; oxide of iron is the product of the combustion of iron... additional examples (a) of chemical changes; (b) of physical changes Is a chemical change always accompanied by a physical change? Is a physical change always accompanied by a chemical change? Give two

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